Rho-cross (Staurogram)

    

The staurogram (P, crossed P) is derived from the Christogram and like the Christogram is a monogram comprising the first two letters of Christ in Greek, Chi (X) and Rho (P).  The staurogram symbol is also called a Rho-cross.  It is used a a control symbol on numerous late Roman issues.  Justinian I issued a scarce nummus with the staurogram between alpha and omega as a "monogram" reverse type.  Angels are sometimes depicted holding a staff  with a Rho-cross.  See Staurogram and Chi Rho.